Based on my personal experience and past posts, it seems both bad coil and injectors going bad, at times seem ok until they become heat soaked.
Do you have access to a scanner?
I am not one of the gurus here but when scanned there is a value, integrator and block learn (I think should be between 128-131?) for both banks. If less, typical suspect is one or more injector failure.
http://www.zr1netregistry.com/forum/...light=injector